Carburetor



April 2, 1940.

M. MALLORY CARBURETOR Filed April 14. 1937 Patented vApr. 2,

UNITED.A S'I`-PI`ES`- PATENT OFFICE CARBURETOB MarionMallory, Detroit, Mich.

Application April 14, 1937, Serial No. 136,947 Y s claims.' -(c1. zei-52) 'Ihis invention relates to new and useful improvements in a carburetor of the type in which the admission of air to the mixing chamber and the degree of vacuum in the latter are controlled by an auxiliary valve connected tothe main throttle valve, the fuel nozzle being located bey tween the two valves.

The 'object of the invention is to provide a carburetor which automatically controlls the mixture ratio soas to insure the utmost economy and eiiiciency under all operating conditions. Such conditions include variations in speed and load, and withal sudden variations in the position of the accelerator.

It is well known, for example, that if the throttle of the usual carburetor is suddenly opened when the engine is operating at a comparatively low speed, the mixture will become too lean until the engine has picked up speed.` On'the other hand; if the throttle opening is suddenly cut down when the engine is operating at high speed, the mixture will momentarily become too rich. Experienced operators understand this and to a certain extent avoid theseextreme conditions.-

With my construction, however, while the main throttle valve is directlycontrolled by the operator through mechanical means, the secondary or auxiliary valve is controlled in part by'air iiow and suction in such a-manner that the ideal mixture ratio is constantly maintained under all conditions. In this connection, the invention embodies' improvements upon the construction disclosedlin my U. S. Patent No. 2,082,710,'issued June 1, 1937.

The construction of the invention, in its preferred embodiment, will be more particularly dei. scribed in connection with the accompanying drawing, .in whichclosed.

'.Fig.. 1 is a vertical sectional view taken centrally of 'a carburetor constructed according to the invention. A

Fig. 2 is. a detail view of the throttle valve, the auxiliary valve, andthe connection between them, as they are disposed when the throttle is Fig. 3 shows the same parts in the positions they normally occupy when the throttle is wide open.

'Ihe invention is illustrated as -applied to a down draft carburetor, which has an air et 5, a

mixing chamber B, and a. fuel mixtureoutlet 'I adapted to be connected with thefengie intake manifold. A venturi B is disposed within the mixing chamber 6.

The bowl 9 adapted to contain fuel which. is

warmed up, additional fuel will be supplied lthrough the nozzle I6. In other Words, the ilow of fuel through the by-pass I is normally cut 01T by a needle valve I'l, which is held to its seat by a spring I8. In starting a cold engine, this needle valve may be raised through the medium l5 of a rod I9, actuated either manually or by a thermostat. A link connects the needle valve to a cam 2I, so that when the needle valve ls opened, the throttle valve 22 will also be slightly opened. 20

The fuel mixture outlet 'l is controlled bya main throttle valve 22 mounted on a stem 23 which is provided with an arm 24 connected to a throttlecontrol rod 25. A link 26 connectsv an offset 21 of the arm 24-to a meteringpln 28, which 25 is provided on\one side with a taper 29 adapted 'to progressively open the channel I3 leading to the nozzle I4 in synchronism with the opening of the throttle, and provided on the opposite side with a taper 30 similarly adapted to open the 30 by-pass I5 .leading to the needle valve Il and v thence to the nozzle I6.

An unbalanced auxiliary 'throttle valve or airA valve 3l, mounted on a stem 32, controls the admission of Aair to the mixing chamber 6. A rod 3,3 pivotally connected to-a lateral extension 34 of the throttle arm 24 telescopes into one end of a sleeve 35. -A rod 36`- secured to the other end of the. sleeve is pivotally connected to an arm 3l secured to the valve stem v32. A light coil 40 spring 38 is disposed on the sleeve 35 between a` iiange 39 formed oi the sleeve and a collar 40 slidably mounted -on the rod 33 but heldv'in a predetermined position thereon by a link 4I that *connects it to the endof the arm 34.

longitudinally of the rod 33 and consequently relieves the tension of the spring until, in wide open position of the throttle, the spring offers little, if any, opposition to the opening of the valve 3|.

The opening movement of the valve 3| is also modied by the influence of a dash pot, which comprises a piston 4| n reciprocable in a cylinder 42 located at one side of the mixing chamber 6 and connected by a. link 43 to the end of the arm 31. The upper end ofthe dash pot cylinder 42 has a constant bleed 44 into the mixing chamber 6. The lower end of the cylinder also bleeds into the mixing chamber through a bleed hole 45 and a channel 46, the capacity of the hole 45 being determined by an adjustable needle 41. The lower end of the cylinder 42 also has a vent 4B into the channel 46,`but this vent is normally closed by a ball valve 49, which is normally held to its seat by a spring 50 except under certain operating conditions as hereinafter explained.

To permit a quick closing of the throttle without material resistance by the dash pot, the lower end of the cylinder is provided with a relief port 5|, opening from the channel 46 and controlled by a ball check valve 52; and its upper end is provided with a port 53, opening to the atmosphere and controlled by a ball check valve 54.

In, the operation of the invention, if the engine is idling, with both valves 22 and 3| substantially closed, and the operator opens the main throttle valve 22, the unbalanced valve 3| will tend to move synchronously with the valve 22, due to the air iiow and pressure against it. 'Ihis movement will be aided by the depression in the dash pot cylinder 42 beneath the piston caused by the suction of air from the cylinder into the mixing chamber.

'I'his synchronous movement of the two valves in opening will take place only if the acceleration of the engine is sucient to create the air flow and suction necessary to overcome the resistance of the spring 38. Under such conditions, the suction will draw sufficient fuel from the nozzle to maintain a normal and substantially uniform mixture ratio. l

However, if the main throttle valve 22 is opened suddenly when the car is traveling slowly, the secondary or air valve 3| will lag behind, due to the pressure built up in the dash pot beneath the piston 4|. If the vacuum in the mixing chamber should become too high, however, due to the dash pot piston moving down too slowly as compared to the pick-up in the speed of the engine, the mixture would become too rich. To correct such a tendency, the channel 46 opens directly into the venturi 8 and the relief valve 49 opens when the vacuum is high enough to overcome the resistance of the spring 50, so that the dash pot is quickly vented as the suction through the venturi accelerates the down ward movement of the piston and the opening of the valve 3|.

'I'he presence of the vent 48 is of the utmost importance when operating at high speed. Without it, if the throttle were closed at high speed and then suddenly opened before the speed was materially checked, the vacuum would surge high and cause too rich a mixture, but with the present construction, the relief valve opens, so that the two valves 22 and 3|, under these conditions, open almost simultaneously, thus maintaining the normal mixture ratio.

It will be understood that the time required to bleed out the dash pot through the bleed 45 is adjusted by the needle 41. 'I'his may be ad- :lusted to give a desired time limit of bleeding so that the opening of the valve 3| will be delayed long enough to allow the engine to pick up on a comparatively rich mixture. If the dash pot bleeds out too rapidly, the valve 3| would open too I soon and cause the mixture to become too lean before the engine attains suillcient. speed to operate on a. normal mixture.

With the needle 41 adjusted for average running conditions, the spring 38 comes into play under certain other conditions. For example, if the car is on a slight grade and the throttle is suddenly opened half way, the dash pot might bleed out and the valve 3| open before the car had picked up proportionate speed. 'I'he vacuum in the mixing chamber would then drop very low and the mixture would be too lean. In such case, however, the spring 38 tends to close the valve or retard its opening until the engine picks up speed and develops suiilcient vacuum in the mixing chamber to overcome the resistance of the spring. The engine will then operate again on the normal mixture.

It will be further noted that on wide open throttle, the spring 38 offers little or no resistance to the opening of the Valve 3|. In opening the throttle, as will be seen by comparing Figs. 2 and 3, the collar 40 moves longitudinally on the rod 33, relieving the tension of the spring. In open position, the taper 29 on the metering pin permits a maximum ow of fuel through the nozzle |4 and the valve 3| opens as fast as the dash pot bleeds out. As above explained, in the event that the bleeding of the dash pot is too slow, as compared to the rate of acceleration, the relief valve 50 opens and prevents excessive vacuum in the mixing chamber, thereby preventing the mixture from becoming too rich.

The second taper 30 on the metering pin 28 is for metering additional fuel through the bypass I5, when starting a cold engine. For this purpose, of course, the needle valve |1 is opened, either manually or automatically, against the resistance of the spring 8. With this improvement, it is not necessary to employ additional choking means for enriching the mixture. When the throttle valve 22 is moved toward open position, the metering pin is raised, permitting fuel to ow from both nozzles |4 and |6 into the mixing chamber and, while the engine is being cranked, the vacuum in the mixing chamber will be so low that the spring 3B will hold the valve 3| closed suiciently for starting. l

The ball check valve 52 merely controls a bleed into the dash pot to allow the piston to move freely upwardly as the throttle is closed. This ball has no spring and is closed by gravity.

'Ihe ball check valve 54 in the same manner bleeds the upper end of the dash pot freely to the atmosphere as the throttle is closed. 'This bleed is provided because the restricted bleed 44 alone is too small to permit a quick closing of the throttle.

It will be noted that, in this invention, fuel both for normal running and for warming up is metered by a single pin operating synchronously with the throttle. No choke valve is necessary. The vacuum in the mixing chamber and the air supply are controlled by engine suction in connection with the operation of the dash pot and the variable tension of the spring 38 in accordance with the requirements of the engine as modified by variou's conditions of speed and load and the position of the throttle.

It will be understood, however. that the detion also embraces such modifications thereof as may fall within the scope of the appended claims.

Having thus described the invention, what I claim asnew and desire to secure by letters Patent, is:

1. A carburetor comprising a fuel mixture` chamber with an air inlet, a fuel inlet, and an outlet adapted to be connected to an engine intake manifold, a main throttle valve controlling. said outlet, an unbalanced auxiliary valve controlling the air inlet and adapted to be opened only by air flow and suction, a dash pot connected to the auxiliary valve to delay its opening when the main throttle valve is opened suddenly, air bleed means from the dash pot into the mixing chamber -providing communication at all times between the dash pot and mixing chamber, and a second air bleed means between the dash potl and mixing chamber normally closed but opening in response to a predetermined vacuum in the mixing chamber to assist the first mentioned air bleed means in venting the dash pot quickly to accelerate opening of the unbalanced v auxiliary valve.

2. A carburetor comprising a fuel mixture chamber with an air inlet, a fuel inlet, and an outlet adapted to be connected to an engine intake manifold, a main throttle valve controlling said outlet, an unbalanced auxiliary valve controlling the air inlet and adapted to be opened only by air-flow and suction, a dash pot connected to the auxiliary valve to delay its opening when the main throttle valve is opened suddenly, a spring tending to close the unbalanced valve, when the main throttle valve is partly open at low engine speeds and low manifold vacuum but ineffectual at high speeds and high manifold vacuum when the vacuum acts on the unbalanced valve and thereby collapses the spring, air bleed means from the dash pot into the mixing chamber .providing communication at all times between the dash pot and mixing chamber, and a second air bleed means between -the dash pot and mixing chamber normally closed but opening in response to a predetermined vacuum in the mixing chamber to assist the rst mentioned air bleed means inventing the dash pot quickly to accelerate opening of the unbalanced auxiliary valve.

3. A carburetor for Ainternal combustion engines'comprising a fuel mixture chamber with an air inlet, a fuel inlet, and an outlet adapted suddenly with the engine operating at low speedv and low vacuum, and means responsive to a predetermined higher vacuum in the mixing chamber at high engine speed for overcoming the aforesaid means to prevent such delay in the opening of the unbalanced valve.

4. A carburetor comprising a fuell mixture chamber with an air inlet, a fuel inlet, and an outlet adapted to be connected to an engine intake manifold, a main throttle valve controlling said outlet, an unbalanced auxiliary valve con.

trolling the air inlet and adapted to be opened only by air flow and suction, each valve having an arm secured thereto for controlling its position,

an extensible link connecting said arms, a spring tending to extend the link when the throttle is partly open, the opening of the two valves being substantially the same when the link is of minimum length, the auxiliary .valve being open less than the main valve when the link is extended, a dash pot connected with the auxiliary valve and tending to delay its opening, said dash pot bleeding into the mixture chamber on the engine side of the auxiliary valve, and a second air bleed means between the dash pot and mixing chamber normally closed but opening in response to a predetermined vacuum in the mixing chamber to 4accelerate the venting of the dash pot and opening of the unbalanced valve.

5. A carburetor for internal combustion engines, comprising a fuel mixture chamber with an air inlet and a mixture outlet adapted to be connected to the engine intake manifold, said chamber being formed with a venturi, a fuel nozzle discharging into said venturi, a main throttle valve controlling said mixture outlet, a

fuel valve controlled by the throttle valve for supplying fuel to said nozzle in synchronism with the main throttle` valve opening, an unbalanced auxiliary valve controlling said air inlet and adapted to be opened only by air flow and suction, the stop means preventing the auxiliaryl valve ,from opening more rapidly than the main throttle valve, adash pot connected to the auxiliary valve and delaying its opening when the main throttle is opened suddenly at low speed and suction, a bleed for said dash pot'into said Venturi, other means to resist the opening of the auxiliary valve when the throttle is partly opened, with a force which varies inversely to the lag of the auxiliary valve behind the main valve, and a second air bleed means between the dash pot and the mixing chamber normally closed but opening in response to a predetermined vacuum in the mixing chamber to assist the first mentioned air bleed in venting the dash pot quickly. whereby the tendency of the auxiliary valve to lag behind the main air valve in the opening is diminished as the throttle is opened Wider.

6. A carburetor comprising a mixing chamber with a fuel inlet nozzle and an air intake,va main throttle valveon the engine side of the chamber, an unbalanced valve for the air intake adapted to be opened only by air flow and suction,

control arms secured to the Vrespective valves,

' a link having two telescopic sections connected one to each arm, an abutment fixed 'on one section, a collar slidable on the other section and constituting a second abutment, an expansile coil spring between thetwo abutments, and a toggle link connecting the slidable collar to a .point on the adjacent arm at a greater distance than the telescopic link from the valve axis, whereby an opening movement of the main throttle valve moves the collar in a direction away from the other abutment.

7. vA carburetor comprising a mixing chamber with butterfiy valves at opposite sides thereof, control arms secured to the respective valves, an extensible link attached to the two arms and including telescopic' sections, an expansile coil spring tending to extend the link, abutmentsA on the link sections between which the spring acts, one of said abutments being movable along a link section, and toggle means connected to said movable abutment and the arm of the throttle valve for moving the abutment along its link section to increase the distance between said abutments as the two control arms are moved equally in a direction to open the valves.

8. In a carburetor, a fuel mixture chamber with an air inlet, a fuel inlet, and an outlet adapted to be connected to an engine intake manifold, a. main throttle valve controlling said outlet, an unbalanced auxiliary valve controlling the air inlet adapted to be opened only by air flow and suction, a dash pot in the form of a cylinder and piston for controlling the opening of the 'un-'- balanced valve, connections between the unbalanced valve anjd the piston of the dash pot. and an air bleed passageway leading from the cylinder to the mixture chamber whereby the vacuum in the mixture chamber acts on thedash pot cylinder to control the opening of the unbalanced valve, a second air bleed leading' from the dash pot cylinder to the mixture chamber, a valve for normally closing the said second air bleed passageway but opening ai: a predetermined vacuum in the mixture chamber whereby the exhausting of the dash pot cylinder and opening of Athe unbalanced valve is accelerated, and push means operatively connecting the throttle and unbalanced valve whereby closing of the throttleV valvecloses the unbalanced valve.

. MARION MAILORY; 1 5 

